Ilya S. Darevsky

The material ancestry and approximate age of parthenogenetic species of Caucasian rock lizards (Lacerta: Lacertidae)

Restriction enzymes were used to assay variation among mitochondrial DNAs from parthenogenetic and sexual species of Lacerta. This permitted identification of the sexual species that acted as the maternal parent of the various hybrid-parthenogenetic lineages. Lacerta mixta was the maternal parent for both L. dahli and L. armeniaca, L. valentini was the maternal parent for L. uzzelli, and L. raddei was the maternal parent of L. rostombekovi. The maternal ancestry of L. unisexualis is not as clear. The sample of L. nairensis was very similar to one from a population of L. raddei and either species could be the maternal parent of L. unisexualis. The parthenogenetic species all had very low nucleotide diversity in absolute terms and in comparison to their sexual relatives. The close similarity between mtDNAs from the parthenogenetic species and their respective sexual maternal ancestor species provides strong evidence for the recent origin of the parthenogens. The low diversity of the parthenogens indicates that few females were involved in their origins; the maternal parents of L. dahli and L. armeniaca could have come from a single population. The patterns of mtDNA variation in Lacerta are very similar to those in Cnemidophorus and Heteronotia, establishing recent and geographically restricted origins as a general feature of parthenogenetic lizards.

Divergence of the Cytochrome b Gene in the Lacerta raddei Complex and Its Parthenogenetic Daughter Species: Evidence for Recent Multiple Origins

Abstract Questions concerning the origin of parthenogenesis in Caucasian Rock Lizards and genetic divergence among bisexual lizards of the Lacerta raddei complex were examined using sequences from the mitochondrial cytochrome b gene. The maternal parent of the parthenogenetic L. uzzelli, L. sapphirina, and L. bendimahiensis was confirmed to be L. raddei. Although substantial variation was revealed among bisexual populations of L. raddei and L. nairensis, very low or no variation was found among the parthenogenetic species. A phylogenetic tree including 11 populations of L. raddei and L. nairensis, as well as 10 populations of its five daughter parthenogens, was constructed. Because of paraphyletic relationships, L. nairensis is considered conspecific with L. raddei. Evaluation of the parthenogenetic species suggests that separate hybridization events between L. raddei and L. valentini might have occurred at least twice. One resulted in L. sapphirina and L. bendimahiensis, and the other one (or more) resulted in L. unisexualis and L. uzzelli. The females involved were distantly related, Lacerta unisexualis and L. uzzelli likely had separate origins, but the females involved were closely related.

Old age, multiple formations or genetic plasticity? Clonal diversity in the uniparental Caucasian rock lizard, Lacerta dahli

Allozyme variation at 35 gene loci is investigated in 161 specimens of the uniparental Caucasian lizard Lacerta dahli from several locations in Armenia and Georgia. All individuals are heterozygotic at 12 loci, and homozygotic at 21 loci. Variation at two loci results in five uniparental clones. One clone is widespread whereas four are geographically restricted and are represented by only one or two individuals. Because successful formation of uniparental clones is rare, and because the biparental species forming them are now allopatric, the most probable explanation for the origin of the observed clonal diversity is either mutation or recombination within the common clone. The rare clones have lower levels of enzyme activity at four loci, suggesting that these organisms may be genetically deficient. Although the evidence points to change in a pre-existing clone, the possibility of multiple origins cannot be ruled out.

The Caucasian Rock Lizard Lacerta rostombekovi: a Monoclonal Parthenogenetic Vertebrate

Key Word Index--Lacerta rostombekovi; Lacertidae; rock lizard; parthenogenesis; unisexuality; clonal diversity; allozymes. Abstract--Among vertebrates, true parthenogenesis (self-perpetuating all-female species) occurs only in reptiles; these species are of hybrid origin. To date, all diploid parthenogenetic reptiles examined exhibit some genetic diversity, resulting in the existence of more than one clone. The sole exception to this is the Caucasian rock lizard Lacerta rostombekovi, which appears to consist of only a single clone.

The Parthenogenetic Rock Lizard Lacerta unisexualis: An Example of Limited Genetic Polymorphism

Abstract. Protein electrophoresis of Lacerta unisexualis from three populations found that 21 of 36 allozyme loci were homozygous, while 14 expressed fixed heterozygotes and one locus was variable. Three clones were detected at the locus Cat-A. Two individuals represent two rare clones while all others form a common clone. Our favored explanation is the mutation of a preexisting common clone rather than multiple origins.

ALLOZYME VARIATION IN THREE CLOSELY RELATED SPECIES OF CAUCASIAN ROCK LIZARDS (LACERTA)

Genetic diversity at 37 allozyme loci was surveyed from Lacerta valentini (4 populations), L. portschinskii and L. rudis (1 population each). The number of polymorphic loci ranged from 1 (L. valentini) to 11 (L. rudis). Mean heterozygosity (direct count) ranged from 0.003 (L. valentini) to 0.071 (L. rudis). Neis (1978) genetic distance ranged from 0-0.03 among populations of L. valentini, 0.127-0.163 between L. valentini and L. rudis and 0.366-0.487 between L. portschinskii and the two other taxa. Indices of genetic variability for species having disjunct distributions were lower than in species with contiguous distributions, similar to the case of insular populations, which have lower values than do mainland populations.

Instability of (GATA) n microsatellite loci in the parthenogenetic Caucasian rock lizard Darevskia unisexualis (Lacertidae)

Mini- and microsatellites, comprising tandemly repeated short nucleotide sequences, are abundant dispersed repetitive elements that are ubiquitous in eukaryotic genomes. In humans and other bisexual species hypervariable mini- and microsatellite loci provide highly informative systems for monitoring of germline and somatic instability. However, little is known about the mechanisms by which these loci mutate in species that lack effective genetic recombination. Here, multilocus DNA fingerprinting was used to study M13 minisatellite and (GATA) n microsatellite instability in the parthenogenetic Caucasian rock lizard Darevskia unisexualis (Lacertidae). DNA fingerprinting of 25 parthenogenetic families, from six isolated populations in Armenia (comprising a total of 84 siblings), using the oligonucleotide (GATA)4 as a hybridization probe, revealed mutant fingerprinting phenotypes in 13 siblings that differed from their mothers in several restriction DNA fragments. In three families (8 siblings), the mutations were present in the germline. Moreover, the mutant fingerprint phenotypes detected in siblings were also present in population DNA samples. No intrafamily variations in DNA fingerprint patterns were observed with the M13 minisatellite probe. Estimates of the mutation rate for (GATA) n microsatellite loci in D. unisexualis showed that it was as high as that seen in some bisexual species, reaching 15% per sibling or 0.95% per microsatellite band. Furthermore, in one case, a somatic (GATA) n microsatellite mutation was observed in an adult lizard. These findings directly demonstrate that mutations in (GATA) n microsatellite loci comprise an important source of genetic variation in parthenogenetic populations of D. unisexualis.

Flow cytometry in biodiversity surveys: methods, utility, and constraints

Flow cytometry of blood is a powerful tool for rapidly sorting individual specimens on the basis of cellular DNA content. During biodiversity surveys, the method enabled the early identification of both cryptic sympatric and allopatric species of Vietnamese ranid frogs. This method may be extremely valuable in sorting individuals from other taxa and geographic regions, especially when cellular DNA content is known to vary among closely related taxa, and in tropical situations where crypsis is a relatively common phenomenon. Protocols for preparation of freezing solution, field procedures, preparation of reference standards, and flow cytometric analysis are provided. The best method for field preservation of blood is freezing in liquid nitrogen; field fixation of blood in ethanol was less efficient and resulted in drastically increased coefficients of variation. Once samples have been transferred to freezer storage, they should not be returned to a lower storage temperature in liquid nitrogen.

Allozyme variation in populations of Lacerta raddei and Lacerta nairensis (Sauria: Lacertidae) from Armenia

Lacertca raddei and Lacerta nairensis have been recognized as two separate species based on morphology and behavior, and each has been implicated as a sexual parent of different parthenogenetic forms. However, recent mitochondrial DNA work failed to distinguish these two as separate species. We examined genetic diversity at 36 allozyme loci from six populations of L. nairensis and four populations of L. raddei. There were no fixed allelic differences between the two. Mean heterozygosity was slightly higher among populations of L. raddei than among populations of L. nairensis. A Distance Wagner phenogram showed that the northernmost population of L. raddei clustered with the L. nairensis populations; the other L. raddei populations clustered together. We suggest that L. raddei and L. nairensis may not be separate species, a finding which has important implications for determining the origins of some parthenogenetic Lacerta.

Clonal variation in the Caucasian rock lizard Lacerta armeniaca and its origin

Clonal variation in Lacerta armeniaca was investigated using allozyme electrophoresis and morphol- ogy. Among the 35 allozyme loci examined, three were variable, which divided L. armeniaca into four clones. One rare clone of L. armeniaca made up the majority of two populations. This contrasts to rare clones in other parthenogenetic Caucasian rock lizards which typically consist of only one or two individuals. Another rare clone, which showed a striking colouration difference, had different allelic composition at two loci. Although mutation is a possible explanation of the origin of the clonal variation, the alternative, multiple origin, is equally likely.